Navigation device with power saving mechanism and method thereof

1. A navigation device with power-saving mechanism, comprising: a GPS receiver, for receiving a satellite signal of GPS to obtain a longitude-latitude information; a first processing unit, for switching from a first mode to a second mode according to a control signal, and outputting a destination information and an enabling signal during the process of switching from the first mode to the second mode, wherein the first processing unit is in disabled mode when the first processing unit switches from the first mode to the second mode; a second processing unit, being enabled according to the enabling signal for comparing the longitude-latitude information with the destination information, and generating a direction information and a distance information according to the comparison result; and a sound playing unit, for selecting two navigation frequencies among a plurality of navigation frequencies as a first frequency and a second frequency according to the direction information and the distance information, and playing a tone signal comprised of the first frequency and a tone signal comprised of the second frequency in sequence.

2. The navigation device with power-saving mechanism of claim 1 , further comprising: a longitude-latitude information register, for storing the longitude-latitude information; a map information register, for providing a plurality of map information; an input unit, comprising at least a button for generating the destination information and the control signal according to the button operation; and a display unit, for displaying a positioning information and a navigation information, wherein when the first processing unit is in the first mode, the first processing unit compares the destination information, the longitude-latitude information with a plurality of the map information to generate the positioning information and the navigation information, and when the first processing unit is switched to the second mode, the map information register, the input unit and the display unit are all in disabled state.

3. The navigation device with power-saving mechanism of claim 2 , further comprising: a first storage unit, for storing the destination information, the positioning information and the navigation information, wherein when the first processing unit is switched to the second mode, the first storage unit is in disabled state.

4. The navigation device with power-saving mechanism of claim 2 , wherein the sound playing unit further plays the corresponding voice signal according to the navigation information.

5. The navigation device with power-saving mechanism of claim 1 , further comprising a power supply unit for providing power to the navigation device, wherein when a power level of the power supply unit drops to a predetermined level, the power supply unit generates the control signal.

6. The navigation device with power-saving mechanism of claim 1 , wherein the second processing unit comprises a second storage unit for storing destination information.

7. The navigation device with power-saving mechanism of claim 1 , wherein the navigation frequencies are a plurality of frequencies arranged in ascending or descending order.

8. The navigation device with power-saving mechanism of claim 1 , wherein the first mode is a pre-set working mode of the first processing unit.

9. A navigating method with power-saving mechanism, comprising: receiving a satellite signal of GPS to generate a longitude-latitude information for indicating a position of a navigation device; switching from a first mode to a second mode according to a control signal, and outputting a destination information and an enabling signal during the process of switching from the first mode to the second mode; comparing the longitude-latitude information with the destination information according to the enabling signal, and generating a direction information and a distance information according to the comparison result; and selecting two frequencies among a plurality of navigation frequencies as a first frequency and a second frequency according to the direction information and the distance information, and playing a tone signal comprised of the first frequency and a tone signal comprised of the second frequency in sequence.

10. The navigating method with power-saving mechanism of claim 9 , further comprising: (a) storing the longitude-latitude information; (b) providing the destination information and a plurality of map information; (c) comparing the destination information, the longitude-latitude information with a plurality of map information to generate a positioning information and a navigation information; (d) displaying the positioning information and the navigation information; and (e) stopping the execution of step (b) to step (d) when switching from the first mode to the second mode.

11. The navigating method with power-saving mechanism of claim 10 , further comprising: (f) storing the destination information, the positioning information and the navigation information; (g) playing the corresponding voice signal according to the navigation information; and (h) stopping execution of step (f) and step (g) when switching from the first mode to the second mode.

12. The navigating method with power-saving mechanism of claim 9 , further comprising a step of storing the destination information according to the enabling signal.

13. The navigating method with power-saving mechanism of claim 9 , further comprising a step of providing the control signal indirectly or directly when a power level of the navigation device dropped to a predetermined level.

14. The navigating method with power-saving mechanism of claim 9 , wherein the navigation frequencies are a plurality of frequencies arranged in ascending or descending order.